Enzyme phenotypes, specifically esterases (EST) and malate dehydrogenase (MDH), were used to characterise different species of Meloidogyne from Chile. Esterase activity was highly polymorphic and was the most useful in the identification of the different species. Using this enzyme it is possible to characterise and identify M. ethiopica in about 80% of samples on grapevine, kiwi and tomatoes. Another three species, M. javanica, M. hapla and M. arenaria, were identified on tomatoes, kiwi and pomegranate with only one or a few populations. It was possible to detect minor atypical (unidentified) phenotypes, generally in mixed populations with M. ethiopica. Only the profiles N1 and H1 of MDH were detected. N1 was not specific and H1 allowed identification of M. hapla. Contaminated nursery stock has probably resulted in serious infestation by M. ethiopica in vineyards in various localities in Chile.
Aqueous extracts of the tree Quillaja saponaria Molina, containing triterpenoid saponins, polyphenols, salts and sugars, were tested against the most important plant-parasitic nematodes present in Chile: Xiphinema index, X. americanum s.l., Meloidogyne hapla, M. ethiopica, Pratylenchus thornei, Tylenchorhynchus sp., Criconemoides xenoplax and Helicotylenchus sp. Three different products were tested in the laboratory: i) QL 1000 ® (whole extract containing saponin and non-saponin fractions); ii) QL ULTRA ® (saponin fraction); and iii) QL NS ® (non-saponin fraction). The results showed that QL 1000 ® had important nematicidal effects at economically attractive doses (e.g., 100 ppm). When used separately, QL ULTRA ® and QL NS ® had minimum nematicidal effects. However, the combined use of both products gave similar results to QL 1000 ® , suggesting a synergy between the saponin and nonsaponin fractions. Based on this, QL 1000 ® was tested in commercial vineyards and table grapes in the Central region of Chile. The use of 30 l ha −1 showed a similar control and fruit yields to synthetic chemical nematicides.
The dagger nematode, (Xiphinema rivesi Dalmasso), a member of the X. americanum group, was first reported in 2002 in Chile (3). X. rivesi is a vector of at least four North American nepoviruses including Cherry rasp leaf virus (CRLV), Tobacco ringspot virus (TobRSV), Tomato ringspot virus (TomRSV), and Peach rosette mosaic virus (PRMV) (2). TomRSV, first reported in Chile in 1984, was associated with raspberry decline and lately with brownline disease in D'Agen prune trees (1), however none of the Xiphinema spp. found in Chile have been reported to transmit this nepovirus. Two virus isolates, TomRSV (prune brownline isolate PBL-08) and Grapevine fanleaf virus (GFLV) (Yellow mosaic isolate GFLV-012), from the virus collection of the Departamento de Sanidad Vegetal, Universidad de Chile were used in transmission tests with a population of X. rivesi found in Chile. X. rivesi is not known to transmit GFLV and this virus was included as a check. The nematodes were extracted from soil from a D'Agen prune orchard, and transmission tests were done in compliance with the criteria proposed by Trudgill et al. (4). Cucumis sativus cv. National Pickling were grown in a growth chamber at 25°C and used as acquisition hosts and transmission bait plants. Acquisition hosts were mechanically inoculated with GFLV or TomRSV, displaying systemic symptoms in 15 to 20 days. Noninoculated cucumber plants were included as controls. Virus infection was confirmed by double-antibody sandwich (DAS)-ELISA before the introduction of nematodes to the soil. After a 20-day acquisition feeding period, the nematodes were wet screened from the soil and added to the healthy bait plants and allowed a 20-day inoculation feeding period. X. rivesi transmitted TomRSV but not GFLV. TomRSV bait plants developed systemic symptoms 5 weeks after the nematodes were transferred. Transmission of TomRSV was confirmed by testing leaf and root sap of bait plants in a DAS-ELISA. High virus concentrations were detected in the roots and leaves of TomRSV symptomatic plants. Bait plants on which nematodes had been allowed to feed following virus acquisition from GFLV-infected or from virus-free control plants tested negative by ELISA. No symptoms appeared on bait plants used for GFLV transmission or the control bait plants. To our knowledge, this is the first report of transmission of TomRSV with a Xiphinema population from Chile and South America. References: (1) J. Auger. Acta Hortic. 235:197, 1988. (2) D. J. F. Brown et al. Phytopathology 84:646, 1994. (3) G. Leal et al. Fitopatología 37:75, 2002. (4) D. L. Trudgill et al. Rev. Nematol. 6:133, 1983.
Isoelectrofocusing of superoxide dismutase (SOD) isoforms was carried out on the extracts of 117 nematode populations belonging to the so-called Xiphinema americanum-group. These populations came from the USA (77), Chile (5), Argentina (1), Venezuela (5), Portugal (15), Italy (2), Crete (1), Montenegro (1), Slovakia (4), Hungary (3), Egypt (1) and India (2). A total of 17 bands of enzyme activity were observed in the screening, whilst single enzyme phenotypes showed from two to eight bands. The high degree of SOD polymorphism of this nematode collection was grouped by cluster analysis into seven distinct homogeneous groups characterised by specific combinations of SOD markers. Sub-groups could be discriminated for larger groups. The small Groups 3 and 5 were constituted mostly by populations from USA east coast states (i.e., NY and PA, respectively). The larger Group 1 resulted from the association of populations coming from various and distant North American States. In other large groups, North American populations were associated with South American and European populations. Overall, the data presented here suggest that geographic separation and different hosts do not seem to be the source of genetic diversity for the X. americanum-group. When an adequate number of populations were collected from the same country, the variability expressed by such a sub-sample was comparable to that of the whole nematode collection. For the first time, homogeneous populations of a large collection of X. americanum-group populations were associated by molecular means in order to explore further approaches that may help resolve the recalcitrant taxonomy and phylogeny of this much debated group.
A nematological survey was carried out in a forest tree nursery in Andujar, southern Spain. Meloidogyne arenaria was found in soil and roots samples from Acacia sp., Biota sp., Juglans regia, Pinus spp., Salix babilonica and Sophora japonica. Pratylenchus vulnus was found in Acacia sp., Cupressus macrocarpa, Juglans regia, Ligustrum japonica, Morus sp., Pinus spp., Populus sp., Salix babilonica and Ulmus pumila. Helicotylenchus sp., Xiphinema americanum and Tylenchorhynchus sp. were found in all the plant species planted in the nursery. Paratylenchus sp., Criconemella sp. and Zygotylenchus guevarai host ranges are also given. The influence of soil storage on the recovery of M. arenaria was studied. At storage temperatures similar to those of the nursery (10-15°C), densities of M. arenaria in soil increased until the sixth week after sampling and were then maintained until the thirteenth week of storage. Incubation temperatures below 16°C during the migration of nematodes through a cottonwool filter, reduced the number of M. arenaria juveniles recovered after 15 h, but increasing migration time up to 39 h could counterbalance this reduction. Pflanzenparasitare Nematoden aus einer sudspanischen Forstbaumschulemit einigen Bemerkungen uber den Einfluss der Probenlagerung auf den quantitativen Nachweis von Meloidogyne arenaria - In einer Forstbaumschule in Andujar, Sudspanien, wurde eine nematologische Untersuchung durchgefuhrt. Meloidogyne arenaria wurde in Boden- und Wurzelproben von Acacia sp., Biota sp., Juglans regia, Pinus spp., Salix babilonica und Sophora japonica gefunden. Pratylenchus vulnus konnte an Acacia sp., Cupressus macrocarpa, Juglans regia, Ligustrum japonica, Morus sp., Pinus spp., Populus sp., Salix babilonica und Ulmus pumila nachgewiesen werden. Helicotylenchus sp., Xiphinema americanum und Tylenchorhynchus sp. wurden an allen Pflanzenarten gefunden, die in der Baumschule angebaut wurden. Ferner werden die Wirtspflanzen von Paratylenchus sp., Criconemella sp. und Zygotylenchus guevarai genannt. Dann wurde auch der Einfluss der Probelagerung auf den Nachweis von M. arenaria untersucht. Bei Lagerungstemperaturen von 10-15°C, die ahnlich waren wie die in der Baumschule, nahmen die Dichten von M. arenaria bis zur sechsten Woche nach der Probenahme zu und hielten sich dann bis zur 13. Woche der Lagerung. Temperaturen unter 16°C wahrend der Wanderung durch ein Baumwollwattefilter verminderten die Anzahl der nach 15h wiedergefundenen Juvenilen, doch konnte eine Verlangerung der Wanderzeit auf 39h diese Verminderung ausgleichen.
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